1. Field of the Invention
This invention relates to liquid treatment, and more particularly to providing support trusses integral with clarifier units in particle laden water, where such trusses minimally interfere with liquid flow and particle removal operations.
2. Description of the Prior Art
Water treatment facilities have been constructed without supports beneath clarifier or settler units. For example, in Kobozev et al. U.S. Pat. No. 4,305,819, floating structures are provided above depending clarifier units. However, vertical partition walls extend substantially below the tubes to define cells and eliminate turbulent flow at the inlet of the tubes.
In a variation of floating supports, in Zimmerman U.S. Pat. No. 4,346,005 an outer end of a tube module is hooked at the top to a launder and has a float at an inner end. As the tubes collect solids, the inner end of the tube module will sink and pivot around the launder hook, changing the angle of the tubes and their settling characteristics.
Also, attempts have been made to make clarifier units which are self-supporting so that they span spaced supports. One such unit, shown in McCann U.S. Pat. No. 3,491,892, has parallel vertical sheets held spaced and joined by baffles. When the baffles between alternate sheets are inclined in opposite directions, the sheets and baffles form truss-like structures which function as liquid-solids separators. Problems have still been experienced in supporting such truss-like clarifier structures. For example, in a rectangular basin embodiment of such structures, the McCann Patent shows an internal cutout for receiving a vertical pipe. The cutout blocks flow through some tubes of the separator, reducing the gallons per hour of throughput. Also, pipes are provided outside of each structure. The outer pipes prevent adjacent truss-like structures from being packed tightly together. As a result, in plan view, valuable liquid-solids separation area is lost.
In a circular settling tank embodiment, the McCann Patent also spaces adjacent separator units by such a large distance that 6-inch wide wooden members are required to stop short circuiting upwardly in radially extending spaces between the adjacent separator units. Although liquid will initially flow from the tubes of one separator unit to the tubes of an adjacent separator unit, it appears that as solids settle in the space between the adjacent units, more and more of such flow will be blocked.
Further, straps hang vertically to support pairs of L angles which extend under the separator units. The L angles also block short circuit flow between adjacent separator units. Thus, in the circular embodiment, the clarifier units of the McCann Patent also lose valuable separation area.
In addition, the McCann units must provide circumferential support transverse to the radial direction (i.e., in a circular or longitudinal direction) of the basin. The circumferential support is provided by cables which are spaced from and extend under the separator units. The cables are tightened by turnbuckles.
Thus, the teaching of the McCann Patent requires; (1) space below each separator unit for either lower support pipes, pipe T's and L angles; or lateral spacer cables and turnbuckles; (2) blocking of short circuit flow through the tubes via two horizontal members; and (3) cutouts in the separator structure to receive the vertical support pipes. An additional limitation of the McCann support structure is that each L angle is under the edge of each separator, which not only concentrates the vertical support stress on the radially extending corners of the truss-like structures, but blocks flow into the pipes at the edges of the separator.
Other separator systems allow separator modules to be directly adjacent to each other. However, one such system uses stainless steel supports having an equilateral triangular cross section with a longitudinal pipe at each apex. Transverse pipes extend between the longitudinal pipes at regular intervals, and diagonal braces extend longitudinally from an apex at one location to an apex at a next location. Although such equilateral triangular trusses have an open framework, they are positioned completely under the separator to provide support. As a result, a substantial (e.g., 36 inches) amount of depth below the bottom of the separator is used for separator support, which can interfere with the operation of sludge collection apparatus which scrapes the bottom of the basin below the separator. Further, since no part of the triangular truss extends above the separator unit, a separate column must extend through a separator unit, or must extend between adjacent separator units to support troughs above the units. This either blocks some tubes of the unit, or requires the units to be cut out, and in any event requires separate structure (in addition to the truss) to support the trough.